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1f77084c8e
Reviewed By: shannonzhu Differential Revision: D34332682 fbshipit-source-id: 498c63851f98dd76502a20a9d1589df5b0c4e7b9
101 lines
3.2 KiB
Python
101 lines
3.2 KiB
Python
#!/usr/bin/env python
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# Copyright (c) Facebook, Inc. and its affiliates.
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"""
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Almost every FBCodeBuilder string is ultimately passed to a shell. Escaping
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too little or too much tends to be the most common error. The utilities in
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this file give a systematic way of avoiding such bugs:
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- When you write literal strings destined for the shell, use `ShellQuoted`.
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- When these literal strings are parameterized, use `ShellQuoted.format`.
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- Any parameters that are raw strings get `shell_quote`d automatically,
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while any ShellQuoted parameters will be left intact.
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- Use `path_join` to join path components.
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- Use `shell_join` to join already-quoted command arguments or shell lines.
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"""
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import os
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from collections import namedtuple
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# pyre-fixme[13] This is too magical for Pyre.
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class ShellQuoted(namedtuple("ShellQuoted", ("do_not_use_raw_str",))):
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"""
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Wrap a string with this to make it transparent to shell_quote(). It
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will almost always suffice to use ShellQuoted.format(), path_join(),
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or shell_join().
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If you really must, use raw_shell() to access the raw string.
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"""
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def __new__(cls, s):
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"No need to nest ShellQuoted."
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return super(ShellQuoted, cls).__new__(
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cls, s.do_not_use_raw_str if isinstance(s, ShellQuoted) else s
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)
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def __str__(self):
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raise RuntimeError(
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"One does not simply convert {0} to a string -- use path_join() "
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"or ShellQuoted.format() instead".format(repr(self))
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)
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def __repr__(self) -> str:
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return "{0}({1})".format(self.__class__.__name__, repr(self.do_not_use_raw_str))
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def format(self, **kwargs) -> "ShellQuoted":
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"""
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Use instead of str.format() when the arguments are either
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`ShellQuoted()` or raw strings needing to be `shell_quote()`d.
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Positional args are deliberately not supported since they are more
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error-prone.
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"""
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return ShellQuoted(
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self.do_not_use_raw_str.format(
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**dict(
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(k, shell_quote(v).do_not_use_raw_str) for k, v in kwargs.items()
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)
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)
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)
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def shell_quote(s) -> ShellQuoted:
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"Quotes a string if it is not already quoted"
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return (
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s
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if isinstance(s, ShellQuoted)
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else ShellQuoted("'" + str(s).replace("'", "'\\''") + "'")
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)
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def raw_shell(s: ShellQuoted):
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"Not a member of ShellQuoted so we get a useful error for raw strings"
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if isinstance(s, ShellQuoted):
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return s.do_not_use_raw_str
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raise RuntimeError("{0} should have been ShellQuoted".format(s))
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def shell_join(delim, it) -> ShellQuoted:
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"Joins an iterable of ShellQuoted with a delimiter between each two"
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return ShellQuoted(delim.join(raw_shell(s) for s in it))
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def path_join(*args) -> ShellQuoted:
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"Joins ShellQuoted and raw pieces of paths to make a shell-quoted path"
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return ShellQuoted(os.path.join(*[raw_shell(shell_quote(s)) for s in args]))
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def shell_comment(c: ShellQuoted) -> ShellQuoted:
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"Do not shell-escape raw strings in comments, but do handle line breaks."
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return ShellQuoted("# {c}").format(
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c=ShellQuoted(
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(raw_shell(c) if isinstance(c, ShellQuoted) else c).replace("\n", "\n# ")
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)
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)
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